In D3D7, there is a rendering state called "D3DRENDERSTATE_ZBIAS" to address Z fighting problem. In D3D9, M$ changed its name to "D3DRS_DEPTHBIAS". However, we've found that some cards does not support this D3D9 rendering state (like our GF4 MX440). Is there any alternative way in D3D9 to do the similar thing? Thank you

Well, the reason the Z-Bias was changed from what I remember, is that while it was supported across hardware, the results you are shooting for werent, and while it looked like it worked on one machine, doesn't mean it would work on another in the way intended. I think that's why they replaced it with the Depth Bias.

Digging around, I found an article that might help you:
http://www.intel.com/cd/ids/developer/asmo-na/eng/dc/pentium4/reference/168495.htm?page=1

Marvelous !!

Projection matrix and viewport... they are worth to try..

Thanks a lot :D